Scalar atomic magnetometers are capable of very precisely measuring a magnetic field strength by optically pumping an atomic vapor and measuring the Larmor precession frequency of the atomic spins within the vapor using a probe laser. An ideal scalar atomic magnetometer measures the magnitude of the magnetic field strength without regard to its direction. However, when the pump laser is circularly polarized and not perpendicular to the magnetic field, nonlinear Zeeman shifts cause the atomic vapor resonance to asymmetrically shift, registering as a small shift in the measured magnetic field. This problem is known as heading error, wherein the magnetometer is sensitive to its orientation relative to the direction of the magnetic field. Other effects such as light shifts or phase shifts associated with the relative orientation of the pump and probe beams can also cause spurious heading errors.